I am 6 feet tall and my weight is 90 KG, which bike should I buy?

As you told that you have been with a Splendor Plus from last 11 years, it seems you take good care of your bike and stays with it for a long time period, plus your budget being not a problem, you should definitely go for the Royal Enfield Classic 350. No doubt, the other bikes are also good each their respective part but the RE Classic 350 would be a gem for lifetime. It comes with a 350 cc engine, producing a lot more power than all the other bikes. New technologies used in the bike makes it fuel efficient as well. It will return a 45 kmpl value and you will be glad to ride it everytime. It comes with self start, disc brake and divided seats as a option over standard Bullet. The bike will suit you the most and will stay with you as long as you want and wont even feel old after next 11 years.

Quick Facts - Royal Enfield Classic 350